The present invention relates to a vulcanization mold for manufacturing pneumatic vehicle tires comprising mold segments for forming the tire tread having, in a plan view onto the radially inwardly positioned mold surface, a honeycomb lamella pattern of a first set of zigzag lamella members, arranged in an at least substantially coinciding direction of extension.
Tread strip patterns for snow tires conventionally have a plurality of narrow sipes. As is well known in the art, the type and manner of the sipe arrangement and design within the individual profiled elements, for example, tread blocks, provides a means of directly effect of the bending stiffness of such profiled elements, especially for optimizing traction and braking properties. An especially advantageous possibility of affecting the bending stiffness is suggested in European Patent application 0 691 222 A2. According to this disclosure, the sipes in the individual profiled elements of the treads strip pattern are provided as a network of uniform or substantially uniform hexagons.
For producing such sipe patterns in the tread strip of a pneumatic vehicle tire, the mold segments of the vulcanization mold, which are to form the correspondingly shaped profiled elements in the tread, must be provided with a honeycomb lamella pattern.
German patent application 196 12 829 A1 discloses a vulcanization mold of the aforementioned kind and suggests, for the formation of a honeycomb pattern of lamellas, to provide a set of zigzag main lamella members anchored within the mold segments and having a main direction of extension so that they are substantially parallel to one another. Two neighboring main lamella members are arranged axis-symmetrically relative to a symmetry axis which extends parallel to the main direction of extension.
For completing the honeycomb structure, straight auxiliary lamellas are anchored within the mold segment. They are connected to the facing corners of neighboring main lamella members and extend perpendicularly to the axis of symmetry. These straight auxiliary lamellas which provide a single honeycomb wall can then be subsequently anchored within the segment or can be positive-lockingly connected to the corners of the zigzag main lamella members.
It was found that this known solution has the disadvantage that the straight auxiliary lamellas are weak points of the honeycomb structure which, especially when they are only anchored to the mold segment, are not sufficiently stable, especially during the actual molding process during which they can be easily bent. The stiffer form-locking connection of the auxiliary lamellas to the corners of the main lamella members, as is suggested by German Patent application DE 196 12 829 A1, requires a time consuming and difficult manipulation because the auxiliary lamellas must be inserted with projections into slots at the corners of the zigzag main lamella members.
The invention has the object to provide a vulcanization mold with mold segments having a honeycomb lamella pattern that is to be constructed of a small number of individual parts but should be very stiff. It is especially an object of the invention to reduce the number of individual parts relative to the known solution of DE 196 12 829 A1.